(A) Field of the Invention
The present invention relates to a method for fabricating an integrated circuit structure, and more particularly, to a method for fabricating an integrated circuit structure with a barrier layer by using a plasma enhanced treating process in an oxidant-containing atmosphere.
(B) Description of the Related Art
In the fabrication of integrated circuit structures, aluminum (Al) and its alloys are widely used for forming electrical connections. However, as device scale continues to be reduced, the number of devices which must be electrically interconnected has increased. The increased number of electrical interconnections required for advanced integrated circuit designs necessitates the formation of extremely narrow interconnect leads. The utilization of aluminum and its alloys for high density interconnect formation is limited by the tendency of aluminum to exhibit thermally induced voiding and electromigration. An additional problem of importance associated with aluminum metallurgy is the relatively higher electrical resistance of aluminum alloys compared to other electrically conductive metals.
To overcome the limitations associated with the use of aluminum for electrical interconnects, other metals such as copper (Cu), gold (Au), and silver (Ag) have been proposed as substitutes for aluminum and its alloys. Copper offers a desirable alternative to aluminum, because of its low resistivity. However, copper diffuses readily in materials commonly used in integrated circuit fabrication, such as silicon (Si) and silicon dioxide (SiO2). This characteristic of copper prohibits the relatively straightforward formation of copper leads in a manner analogous to that used in the formation of aluminum interconnects. Therefore, the implementation of aluminum for the formation of electrical interconnects between aluminum and copper requires that special processes and materials be provided to overcome the problems of diffusion and adhesion associated with the use of copper.